Background: The aim of the study was to investigate the correlation between serum magnesium (Mg) level and cardiac valve calcification (CVC) in patients with chronic kidney disease (CKD).
Methods: A total of 232 CKD patients hospitalized from August 2016 to December 2020 were divided into CVC and non-CVC groups. Their clinical data and laboratory examination results were compared, the risk factors for CVC in CKD patients were explored using logistic regression analysis, and Spearman's method was used to analyze the correlation between serum Mg level and CVC degree. According to the tertiles of mean serum Mg level, they were assigned into low serum Mg group (≤ 0.96 mmol/L), middle serum Mg group (0.97 - 1.07 mmol/L), and high serum Mg group (≥ 1.08 mmol/L). The relationship of serum Mg level with CVC risk in CKD patients was analyzed through the Cox regression model, and a prediction model was established using independent risk factors.
Results: Long CKD duration, low serum Mg level, high serum phosphorus (P) level, and high CKD stage were independent risk factors for CVC. Serum Mg level was significantly negatively correlated with the severity of CVC (r = -0.743, p < 0.05). The risk of CVC was significantly higher in low serum Mg group than that in high serum Mg group [hazard ratio (HR) = 2.852, 95% confidence interval (CI): 1.325 - 6.432, p = 0.005]. A CVC prediction model was established based on independent risk factors as follows: CVC predictive value = EXP [0.491 - 0.546 (CKD duration) - 0.454 (serum P level) + 2.145 (serum Mg level) - 0.812 (CKD stage)]/1 + EXP [0.491 - 0.546 (CKD duration) - 0.454 (serum P level) + 2.145 (serum Mg level) - 0.812 (CKD stage)]. The area under curve of the model was 0.750 (95% CI: 0.822 - 0.965), and that of the CVC prediction model for CKD patients in test set was 0.774 (95% CI: 0.761 - 0.975), showing no significant difference from that in training set (p > 0.05).
Conclusions: Low serum Mg level serves as an independent risk factor for CVC in CKD patients, and may increase the risk of CVC. Therefore, the serum Mg level in CKD patients should be corrected timely in clinical practice.